Long twisted pair reads digita
this circuit is a simple and economical interface for remote ic thermal sensors. the temperature sensor (max6576), an absolute temperature-to-period converter that integrates the sensor with the necessary signal electronics, connects to the receiver (a max9140 comparator) using a twisted-pair cable that carries power to and signals from the sensor.
a similar version of this article appeared in the november 5, 2007 issue of ed magazine.
the best choice for midrange, low-to-medium-accuracy temperature measurements (considering size, cost, performance, and ease of use) is an ic temperature sensor—assuming the circuits to be interfaced with the sensor reside on the same board or in the same box. most ic temperature sensors are designed for applications in which the circuits to which they connect are nearby, so the inclusion of sensing, digitizing, and signal-processing functions in a single ic greatly simplifies the design of such sensors and the data-acquisition interface.
some applications, however, require the acquisition of temperature data from locations quite remote from the power supply and data-processing electronics. you must exercise extra care with such systems, because any deterioration in the signal from the remote sensor can degrade the measurement quality.
choosing to digitize and process the signal at the point of measurement (near the sensor) greatly reduces the problem of signal integrity, but that approach also complicates the interconnection and raises the problem of supplying power to the circuit. either design option (signal processing remote or at the sensor) requires cabling that is complex or expensive or both.
the circuit of figure 1 provides a simple and economical interface for remote ic thermal sensors. the temperature sensor (max6576) is an absolute temperature-to-period converter that integrates the sensor with the necessary signal electronics. it connects to the receiver (a simple comparator) using a twisted-pair cable that simultaneously carries power to the sensor and signals from the sensor.
figure 1. these two ics enable the remote acquisition of temperature data over a twisted-pair cable.
figures 2, 3, and 4 show the circuit waveforms using a short cable connection of 60cm (about two feet) between sensor and receiver. figures 5 and 6 show the receiver's input and output pulses using a twisted-pair cable connection of 1000m (about 3300 feet). measurements of the receiver's pulse-to-pulse output jitter (where total measurement error is the ratio of jitter to the signal period) indicates that the jitter influence is negligible, even with the long cable.
figure 2. receiver output pulse using a short 2-foot cable, 20µs/cm.
figure 3. receiver output pulse using a short 2-fooot cable, 400µs/cm.
figure 4. receiver input pulse for a short 2-foot cable.
figure 5. receiver input pulse for a long 3000-foot cable.
figure 6. receiver output pulse for a long 3000-foot cable.
with its ts0 and ts1 terminals connected as shown in figure 1, the max6576 exhibits a digitizing conversion constant of 10µs/k. as seen in figure 3, the output pulse period at room temperature (300k) is 3ms, which corresponds to a repetition rate of about 333hz.
at the receiving end, you can recover the temperature data from the comparator-output pulses with a simple timer/counter routine executed by a microcontroller, or in analog form using a constant-slope, linear sawtooth generator synchronized with the received pulses, and followed by a peak sample/hold (s/h) converter. this transmission scheme can also be used with temperature-to-frequency converters and other sensors.
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Long twisted pair reads digita
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a similar version of this article appeared in the november 5, 2007 issue of ed magazine.
the best choice for midrange, low-to-medium-accuracy temperature measurements (considering size, cost, performance, and ease of use) is an ic temperature sensor—assuming the circuits to be interfaced with the sensor reside on the same board or in the same box. most ic temperature sensors are designed for applications in which the circuits to which they connect are nearby, so the inclusion of sensing, digitizing, and signal-processing functions in a single ic greatly simplifies the design of such sensors and the data-acquisition interface.
some applications, however, require the acquisition of temperature data from locations quite remote from the power supply and data-processing electronics. you must exercise extra care with such systems, because any deterioration in the signal from the remote sensor can degrade the measurement quality.
choosing to digitize and process the signal at the point of measurement (near the sensor) greatly reduces the problem of signal integrity, but that approach also complicates the interconnection and raises the problem of supplying power to the circuit. either design option (signal processing remote or at the sensor) requires cabling that is complex or expensive or both.
the circuit of figure 1 provides a simple and economical interface for remote ic thermal sensors. the temperature sensor (max6576) is an absolute temperature-to-period converter that integrates the sensor with the necessary signal electronics. it connects to the receiver (a simple comparator) using a twisted-pair cable that simultaneously carries power to the sensor and signals from the sensor.
figure 1. these two ics enable the remote acquisition of temperature data over a twisted-pair cable.
figures 2, 3, and 4 show the circuit waveforms using a short cable connection of 60cm (about two feet) between sensor and receiver. figures 5 and 6 show the receiver's input and output pulses using a twisted-pair cable connection of 1000m (about 3300 feet). measurements of the receiver's pulse-to-pulse output jitter (where total measurement error is the ratio of jitter to the signal period) indicates that the jitter influence is negligible, even with the long cable.
figure 2. receiver output pulse using a short 2-foot cable, 20µs/cm.
figure 3. receiver output pulse using a short 2-fooot cable, 400µs/cm.
figure 4. receiver input pulse for a short 2-foot cable.
figure 5. receiver input pulse for a long 3000-foot cable.
figure 6. receiver output pulse for a long 3000-foot cable.
with its ts0 and ts1 terminals connected as shown in figure 1, the max6576 exhibits a digitizing conversion constant of 10µs/k. as seen in figure 3, the output pulse period at room temperature (300k) is 3ms, which corresponds to a repetition rate of about 333hz.
at the receiving end, you can recover the temperature data from the comparator-output pulses with a simple timer/counter routine executed by a microcontroller, or in analog form using a constant-slope, linear sawtooth generator synchronized with the received pulses, and followed by a peak sample/hold (s/h) converter. this transmission scheme can also be used with temperature-to-frequency converters and other sensors.
5G正在为新时代制造业行业带来革命性的变化
新加坡大力发展无人机高新科技技术，将推出一大批无人机用于物流运输
选择一个电阻值范围介于方程式1与2所定义电阻值之间的外部电阻器
联通5G沃视频美丽中国频道正式上线
iPhone8十周年：iPhone8全新设计！极具纪念意义，黑科技不止是黑科技
Long twisted pair reads digita
大算力自动驾驶SoC芯片主要玩家及出货量排名
飞思卡尔推出工业级32位微控制器全新Kinetis E系列
福特将发行Model E ,它会让特斯拉颤抖吗?
储能BMS和动力BMS区别及储能新国标颁布
亿纬锂能与容百科技签署战略合作协议
12.5K~50K信道石英晶体滤波器ABCD系列
智能镜面电视带你享受惬意智能的家居生活时光
戴森推出新款加湿空气净化风扇，可持久监测并长效清除甲醛
基于千兆网的FPGA多通道数据采集系统设计
移动服务收入将受益于5G普及
Keysight MSOX3012T示波器
普渡无人化全自动消毒机器人 奔赴石家庄医院抗疫
玻璃管转子流量计的应用与构造
还在等小米6？别又被雷军耍猴了，华为正式发布P10，指纹识别迎来大改